Method of charging cellulose digesters and the like and means therefor



July 10, 1928. 1,676,691

P. A. FRESK METHOD OF CHARGING CELLULOSE DIGESTERS AND THE LIKE AND MEANS THEREFOR Filed Nov. 24, 1924 2 Sheets-Sheet l July 10, 1928. 1,676,691

P. A. FRESK METHOD OF CHARGING CELLULOSE DIGESTERS AND THE LIKE AND MEANS THEREFOR Filed Nov.24, 1924 2 Sheets-Sheet 2 [In/e n/or Patented July 10, 1928.

UNITED STATES PATENT OFFICE.

PER ALBERT FRESK, OF ROBERTSFORS, SWEDEN.

METHOD OF CHARGING OELLULOSE DIGESTERS AND THE LIKE AND MEANS THEREFOR.

Application filed November 24, 1924, Serial No. 752,072, and in Sweden May 13, 1924.

In charging cellulose digesters the method of causing the chips to fall down into the digester' through the influence of their own weight has generally been practised, the chips having been guided by a tube or the like extending down into the neck of the digester. The gravity acting in this'process brings about a certain packing effect between the chips, which effect, however, is by far not sutlicient for introducing any larger charge into the digester. Moreover, as the falling chips are always met and counteracted by the air expelled from the digester,.according as the latter is being filled, the effect of gravity, and thus also the density of the body of chips packed is reduced.

In order to bring about a greater packing efi'ect, one therefore had to resort to two methods, one of which consists in manually pounding the chips together in the digester,

according as the latter is being filled. According to the second method, an apparatus has been introduced through the upper neck of the apparatus, said apparatus being lowered to a suitable depth, and consisting of a bucket wheel built in one unit together with an electric motor, or adapted to be driven by such a motor. As hereinbefore described, the chips are caused to fall down into the digester, but in so falling down the chips will meet the said bucket wheel and are hurled outwards by the same in a di rection toward the periphery of the digester.

The object of the present invention is to avoid the said drawbacks and also to bring about a degree of packing, that is to say, an amount of charge, and a uniformity in the different parts of the massof chips,

which by far exceeds the amount of charge and the degree of uniformity that could heretofore be attained, without the time required in the filling process being materially increased.

The method according to the invention which is carried out mechanically throughout, that is to say, without any heavy manual labor, is principally characterized by the charge, the chips being driven into the digester under the influence of an air current or air currents, while at the same time a rarefaction of air or a vacuum is produced in the digester. The method is carried out so that the air, on having brought the charge into the digester, is removed therefrom in such a manner that the escaping air will not counteract the inflowing air bringing the charge along with it.

The requisite air current may of course be produced by means of a suction or pressure fan, or a compressor, or by any equivalent means. After the air has been forced into the digester, depositing the charge therein, it may, if deslred, escape through an outlet in the digester proper, which outlet will then have to be so situated that the escaping air cannot counteract the inflowing air. It is preferable, however, to produce a closed continuous air current in such a manner that, after the air which, for instance, originates in a suction fan, has entered the digester and deposited the chips, it will be led back to the fan in order to be again forced into the digester, and so forth. In addition to the advantage that the digester need not then be provided with a special air outlet, cooling of the digester is prevented, in that the circulating air will, inthe course of the entire charging operation, maintain approximately the same temperature as in the interior of the di ester.

The accompanying rawing illustrates an example of an apparatus suitable for carrying out the method according to the present invention, in which an air current clrculating in the manner set forth is caused to act. Fig. 1 is a vertical section of the apparatus when placed in operative position above a digester. Figs. 2 and 3 show horizontal sections on the lines AA and BB respectively in Fig. 1. Figs. 4 and 5 show details of the apparatus viewed from above.

In the drawing, 1 is the digester having a container funnel 2 rigidly disposed thereabove, in which funnel the chips may be stored, ready to be charged, and where they are retained by means of the damper 12. The apparatus adapted for the method according to the invention may be accomodated in the space between the digester 1 and the funnel 2, and it is preferably carried by a suitable traveller device not shown, by means of which it may be moved into the said space when charging is to take 'place, and then back again to the side of the digester. In the example shown the apparatus consists of a cylindrical casing provided with an inlet 3 and an outlet 4 for the air, both being connected with a suitable fan device by means of a closed conduit not shown. The inlet 3 communicates with an ejecting device consisting of the tubes 5 and 6, the first one of which is connected to the funnel 2 when the apparatus is in the operative position. Connected to the lower edge of the tube 6 is a tube 7 consisting of sheet metal, fabric, leather or the like. This tube 7 may be constructed so that it may or may not be distended and contracted in' the longitudinal direction. In both cases the tube 7 extending down into the neck of the digester serves as a guide member for the stream of chips andthe air current.

By means of a tube adapted to be contracted it is possible to bring the Whole apparatus to the side of the digester also when the distance from the chip container to the digester is very small, so that raising of the apparatus is impossible. In order to permit of being'distended or contracted, the tube 7 is attached all over its entire length to a number of rings 8 carried by ropes 9 suspended from rope drums 10. These latter are adapted to be rotated at the same time by means of a gearing shown in Fig. 4, so as to wind up and to unwind the ropes. The air outlet 4 communicates with the space about the tube 7. under the lower end of the tube 7 is a conical baffle 11 adapted to spread the major portion of the chips outwardly toward the periphery of the digester, while at the same time being shaped so as to allow part of the chips to pass therethrough along and about the vertical axis of the digester. Provided about the space on the inside of the air inlet 3 as well as about the space inside the air outlet 4 are damper devices 14 (Fig. 2) and 15 (Fig. 3) respectively, consisting preferably of perforated wallsadapted to be rotated relatively to each other, the rotation of the said walls permitting a control in such a manner that the air coming through the inlet 3 will be uniformly distributed around the injecting device, while the air escaping through the outlet 4 is acted upon uniformly by suction about the space outside the tube 7.

The apparatus is used and acts in the following manner:

After the injecting apparatus has been moved into the space between the digester and the funnel 2, the said apparatus is raised in some way or other, and the tube 7 is locked by means of hooks or the like, onto the funnel 6 or to the extension thereof. Afterwards the apparatus is again lowered so that it is caused torest on the flange of the digester, while the tube 7 extends down into the digester. Or, when tube 7 is constructed so as to permit of being distended, the rope 9 is unrolled, after the apparatus has been moved onto the flange of the digester, whereby tube 7 is caused to extend down into the digester. The fan connected to the air inlet 3 and to the air outlet 4 re- Suspended in the ropes spectively is started, and the dampers of the funnel 2 are opened. The chips I falling down from the funnel into the injecting tube 5 are then forcibly entrained by the air flowing forth in the space between the tubes 5 and 6, and are moved through the tube 7, at a corresponding great velocity, down into the digester, where the chips are packedin the manner hereinbefore set forth. After the air has performed this work it flows 'back to. the fan under the influence of the suction through the outlet 4,,and from the fan the air is again introduced into the digester, and so forth, in a continuous circulation as long as the charging operation lasts. Toward the end of charging the tube 7 may be hoisted according as the upper surface of the charge rises, whereby an intense packing effect is also obtained in the topmost portion of the digester.

With respect to the construction of the apparatus, modifications may of course be made from the embodiment shown and described, without departing from the principle of the invention. The container funnel 2 need not be present, provided the chips may be directly introduced into the injecting tube 5. by means of some other device. The injecting device per se may of course be made in any suitable way other than that shown in the drawing.

What I claim as new and desire to secure by Letters Patent of the United States of America is 1. An apparatus for charging pulp digesters consisting of an injecting device exhausting into the digester, a tube adapted to be contracted and distended longitudinally and extending from said injecting device into thedigester, an air inlet communicating with said injecting device, a storing space for the charge also communicating with said injecting device, and a fan communicating with said air inlet for producing an air current.

2. An apparatus for charging pulp digesters consisting of an injecting device exhausting into the digester, a tube of flexible material extending from said injecting device into the digester, rings attached longitudinally of said tube, ropes carrying said rings, rope drums, onto which said ropes may be wound and from which they may be unwound, a gearing connecting said rope drums mutually so as to permit of their being rotated at the same time, an air inlet communicating with said injecting device, a storing place for the charge also communicating with said injecting device, and a fan communicating with said air inlet for producing an air current.

3. An apparatus for charging pulp digesters consisting of an injecting device exhausting into the digester, a tube of flexible material extending from said injecting device into the digester, rings attached longitudinally of said tube, ropes carrying said rings, rope drums, onto which said ropes may be wound and from which they may be unwound, a gearing connecting said rope drums mutually so as to permit of their being rotated at the same time, a conical screen carried by said ropes under the lower end of said tube, said screen consisting of concentric annular rings placed so that suit able spaces are left open for the" passage of a small portion of the charge, whereas the major portion is uniformly spread closer to and adjacent the periphery of the digester, an air inlet communicating with said injecting device, a storing space for the charge also communicating with said injecting device and a fan communicating with said air inlet for producing an air current.

4. An apparatus for charging pulp digesters consisting of an injecting device exhausting intothe digester, an air inlet communicating with said injecting device, a storing space for the charge also communicating with said injecting device, a tube extending from said injecting device into the digester, an air outlet communicating with the space around said tube, a damper disposed around said injecting device to control the uniform distribution of the incoming air, a damper disposed around the space outside said tube to control the uniform distribution of the escaping air, and a fan communicating with said inlet as well as said outlet for producing an air current in closed continuous circulation through said inlet and outlet.

5. In the process of charging and pack ing pulp digesters with chips to secure a close and uniform packing of the chips therein, the steps which comprise establishing a circulating gaseous current into and out of the digester, and introducing a charge of chips into the gaseous current entering the digester whereby the chips are impelled into the digester.

6. In the process of charging and packing pulp digesters with chips to secure a close and uniform packing of the chips therein, the steps which comprise establishing a circulating air current into and out of a digester, and introducing a charge of chips into said air current entering the digester.

7 A pulp digesting apparatus comprising a digester, an injecting device in communication with the digester, said digester having an outlet, a fan connected with said outlet and said injecting device to establish a circulating gaseous current through said digester, and means to introduce a charge of chips into said injecting device.

In testimony whereof I afiix my signature.

PER ALBERT FRESK. 

